1. Technical Field of the Invention
The present invention relates to telecommunications systems and, in particular, to the application of caller id functionality to mobile stations within a mobile telecommunications network.
2. Description of Related Art
With the introduction of Signaling System No. 7 (SS7) telecommunications systems, and other SS7 based signaling protocols, a number of advanced subscriber features are now provided to mobile subscribers. One such subscriber feature or service is the ability to enable the called party mobile subscriber to ascertain the identity of the calling party subscriber when an incoming call is received. As an illustration, a directory number associated with the calling party subscriber terminal is displayed to the called party subscriber as the incoming call is terminated to the called party subscriber terminal. The called party subscriber then has the option of not answering the incoming call from a unwanted individual. Moreover, such calling party directory numbers can also be stored and utilized later by the called party subscriber to return calls to the previous calling party subscribers.
With the introduction of the Global System for Mobile (GSM) communications standard, a number of other special subscriber services are available to enable mobile subscribers to not only communicate data which represent voice, but also other unstructured data over the serving Public Land Mobile Network (PLMN). An example of such special subscriber services is the communication of unstructured data between a mobile station and a serving mobile telecommunications network. Messages like Short Message Service (SMS) messages are utilized to communicate text data between a serving mobile switching center (MSC) and a mobile station. Using SMS messages, the serving MSC or any other connected node can transmit user information to the mobile station and have the mobile station store the received user information in an associated Subscriber Identity Module (SIM) card. As an illustration, SMS messages can then be used to update a SIM card with the latest menu options, speed dial lists, subscriber feature information, etc.
Another example of unstructured data communications comprises the Unstructured Supplementary Service Data (USSD) message. Using USSD messages, a mobile telecommunications network is able to transparently communicate text data with a mobile station. For example, a mobile station can receive and display text messages on an attached display unit and subsequently return a reply message back to the mobile network.
A mobile subscriber, however, is not capable of receiving any of the above services and messages unless the mobile station is turned on and is responding to the paging performed by the serving MSC. For example, if the mobile station is outside of the effective radio coverage area or turned off, all incoming calls towards the unreachable mobile station are unsuccessfully terminated. In order for the mobile station to subsequently determine the identity of the previously attempted incoming call, the mobile station has to either be associated with voice mail or be called back by the same calling party. Such alternatives are disadvantageous for a number of reasons. Not all calling party subscribers leave voice messages along with their directory numbers with the called party's voice mail system. The called party mobile station must also repeatedly access its voice mail system and inconveniently check its messages each time after being turned on or traveling back into the service area.
Accordingly, there is a need for a mechanism to enable the serving mobile telecommunications network to automatically inform the mobile station of the calling party directory numbers associated with the attempted incoming calls received and directed towards the mobile station while the unit was turned off or out of reach.